In wheel-type odometers such as those currently used in motor vehicles to register the distance traveled, there is typically employed in a 100,000.0 mileage indicator one decimal wheel, six digit wheels and a plurality of pinion carrier-pinion gear sets equal in number to the figure wheels to transfer drive therebetween. In a conventional assembly, the pinion carriers fit between the wheels and each have a tab that fits into a channel in an odometer module frame to prevent carrier rotation. And the pinion gears have a circular groove by which they are rotatably supported in notches in the respective pinion carriers at a specified angle from the tabs; this to control their position in the module assembly. Each pinion gear has three locking and three transfer teeth on one side and six drive teeth on the other.
The locking teeth of each pinion gear fit into a locking ring inside one surface of respective wheel and within design tolerances, a certain amount of pinion gear rotation is possible. Each wheel to the left also has an internal gear engaged with the drive teeth of an adjacent pinion gear and within design tolerances a certain amount of wheel rotation is possible before wheel transfer has begun. Each of the wheels as observed from right to left thus has an accumulative angular rotation possible because of the clearances in the locking teeth and drive teeth in each of the previous wheels. As a result, the extreme left hand or 100,000 mile wheel has the greatest amount of clearance. Moreover, there may be because of the design of the pinion gear and wheel gears, additional transfer gear clearance when the wheel digits are at "0" causing the wheel member numerals to appear lower than the odometer's normal centerline. After a period of operation time, the odometer shaft which rotates inside each wheel works against these rotational clearances to bring all the wheels into alignment. In the meantime, there will be progressive so-called "backward" droop reading right left and it has long been a desire to limit the maximum amount of backward droop of the numeral "0" on the 100,000 mile wheel to a substantially smaller amount than the summation of all the wheel gear and pinion gear clearances.